The premise of these studies is that detection of candidal antigen(s) in clinical body specimens will facilitate early diagnosis of invasive candidiasis. Specific objectives are: 1. To rigorously evaluate the utility of 3 RIAs to candidal mannan-proteins in prospective studies of granulocytopenic patients. The utility of a mannan RIA with wide serotypic cross-reactivity will be compared to 2 RIAs of greater serotypic specificity; to the detection of IgM and IgG anticandidal antibodies; and to routine diagnostic procedures. In subgroup analysis, RIAs will be compared to simpler immunoassay procedures (objective 2), to new antigen probes (objective 3), and to GLC assays. 2. To improve the mannan-protein assays for immunodiagnosis by: Developing rapid one-step, two-site antigen detection assays with available polyclonal antisera and with monoclonal antibodies; adapting our competitive inhibition RIAs to simple ELISA and our pilot agglutination assays for gneral serology laboratiries; developing a simpler, more efficient extraction for mannan-proteins from serum and urine by solid-phase adsorbtion; developing high avidity monoclonal antibodies for use in RIAs and other assays, and for use in novel diagnostic probes (objectives 3,4). 3. To identify by novel immunohistochemical, immunochemical, and biochemical techniques, new antigen probes for immunodiagnosis of invasive candidiasis. We propose to directly identify nonmannan antigens and different epitopes of mannan-proteins elaborated in vivo during human infection by this method and develop new probes to them. In addition, we will identify by Western blotting the candidal antigens which are predominant immunogens during invasive infection; correlated these immunogens with the immunohistochemistry, and develop assays to immunogens which appear likely to have diagnostic utility. 4. To use experimental models of candidasis to evaluate new diagnostic techniques: endocarditis and meningitis for in vivo scintography of radiolabeled candidal antibodies and for flow cytometry (FACS) of phagocytes; pneumonia for immunoperoxidase cytology of bronchoalveolar lavage cells; and kidney and bladder candidiasis to characterize mannan antigenuria.